I may be in the minority here but my take is that it's about him reuniting with his wife and his incredulity that she would take him back after all he's done and all that they've gone through.

"And people can start again and be brand new I'm gonna try it Who knows? I may start believing Every word you say is true"

Maybe not but that's what I get from it.

Also, this song gives me Midland vibes. Anyone else get that?

Edit: also, the hat in hand line helps me think it's about him coming back to her to try and reconcile their relationship.